Robotic Systems and Applications
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Nonlinear dynamic behavior analysis of bridge pier impacted by a moving barge
Get PDFThe contradiction between ships and bridges is becoming increasingly prominent, and ship-bridge collision accidents occur frequently. However, the existing researches focus on the impact force, the bridge will be simplified to a single pier, but the single pier collision model cannot accurately reflect the dynamic behaviors and damage evolution process of collision. In order to solve this problem, a refined barge-whole bridge collision finite element model is established. This model can be used to analyze the dynamic characteristics of barge and whole bridge collision. According to finite element results, the impact force can be divided into four phases: (1) Linear elastic phase, (2) Buckling unstable phase, (3) Plastic deformation phase and (4) Unloading phase. The impact velocity and barge mass change the initial kinetic energy of the barge, which is positively correlated with the peak impact force and the duration of the impact force. Compared with the barge-single pier collision model, the barge-whole bridge collision model is more systematic and comprehensive in reflecting the dynamic behavior of collision. In this paper, the research of barge-bridge collision provides a scientific basic theoretical basis for the design of anti-collision facilities, the proposal of post-collision damage assessment techniques and the development of bridge post-collision warning system
Experiment and analysis of active vibration isolation system based on rigid pedestal using SDOF actuator
Get PDFThis paper is about the active-passive isolation system based on single degree of freedom electromagnetic actuator and focuses on different control effect of different measure points. In view of this problem, the authors analyze the vibration characteristics of the active and passive vibration isolation systems of electromagnetic airbags under single and multi-vibration isolators. Then they decompose the rigid pedestal vibration into two orthogonal components, the vertical translation and the fix axis rotation. After that compare simulation and experiment results in terms of the control effect when the single active-passive isolator location varies. Finally, the authors draw a conclusion about the reason why the rigid pedestal vibration can be globally controlled by arranging more than 3 active-passive isolations and design a multiple isolator system experiment to verify
Amorphous FeVO4 as high-capacity cathode precursor for lithium second battery
Get PDFVarious vanadates have been investigated to accelerate the development of advanced technologies, especially in the area of electronics. Amorphous FeVO4 was synthesized by the liquid phase precipitation method. This precursor was firstly discharged and then charged as cathode material of lithium second battery, in which the valence of two kinds of metals can be changed. Thermal analysis (TG-DTA), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) have been used for their characterization. The result revealed the existence of two pairs of redox couples, Fe3+/Fe2+ and V5+/V4+. The electrochemical investigation has shown that at higher potentials amorphous FeVO4 can react with 1, 1.5 and 2 mol Li, respectively
Dual-phase-lag model on microelongated thermoelastic rotating medium
Get PDFThe dual-phase-lag (DPL) model is applied to study the influence of rotation on a two-dimensional micro-elongated thermoelastic medium problem. Mechanical force along with the layer of the elastic half-space interface and micro-elongated thermoelastic half-space is applied. The analytic expressions for displacement component, temperature distribution, micro-elongational scalar and stress components have been derived and represented graphically. The rotation has been studied in the presence DPL model and Lord-Shulman theory
Successful balance of occlusal plane using functional orthopedics appliance
Get PDFIn this article, the treatment of two clinical cases is presented, in which the two patients showed distocclusion, severe overbite, required correction of the occlusal plane and movements of the mandible. Both were treated with functional orthopedic appliances In the first case. the patient was 4 years and 5 months old, and in second, 10 years 10 months old. Both had a significant pathological occlusal plane with a large difference in the height between the right and left sides. The lateral movements of the mandible showed completely different Functional Masticatory Angle Planes. The protrusion and opening movements of the mandible also showed deviation. The Functional Orthopedic appliance would advance the position of the mandible forward and would produce better responses if it were able to touch the incisors in the specific area. The forward mandibular position would activate the Ihh (Indian Hedgehog) and produce replication of the mesenchymal cells in the condyle and glenoid fossa. Moreover, it could produce an increase of mandibular length, and regulate the factors of mandibular condylar growth. The space produced between the occlusion as a result of the change to the forward mandible position must stimulate tooth eruption to correct the curve of the occlusal plane. Both cases showed balance of the occlusal plane and same functional masticatory angle Planes. Furthermore, the protrusion and opening movement of the mandible were corrected and no longer showed deviations. Note in both cases that the stability of the mandibular advancement occurred due to maintenance of twice as long to achieve incisor contact
Cephalometric components and their implications in mandibular positioning
Get PDFThe mandibular position is determined by several physiological factors, which should be considered for diagnosis, therapy and stability. Sixty-eight lateral skull radiographs were taken and plotted to determine the relationship of the occlusal plane with the mandibular position among others. A Spearman statistical analysis was performed to determine the relationship between these variables. The occlusal plane showed a statistically significant correlation with mandibular position
Composite plate damage localization based on modal parameters
Get PDFA damage localization method based on natural frequency was proposed in order to complete the nondestructive diagnosis of a composite plate. The relationship between the damage position and the natural frequency of the composite plate was studied both qualitatively and quantitatively. Furthermore, the damage localization method proposed in this paper was proved by simulation and experimentation, with the results showing that this method can locate the position where the stiffness of the composite plate decreased in both simulation and experiment. Finally, the damage localization method based on natural frequency can be applied for non-destructive diagnosis of a delamination composite plate
Effect of material characteristics of explosive on formation of collinear explosively formed projectile from warhead with double layer liners
Get PDFIn order to obtain the effect of material characteristics of explosive on the formation of collinear explosively formed projectile (EFP)from warhead with dosuble liners, the LS-DYNA simulation software was used to simulate and analyze the forming process of collinear EFP from warhead with five explosive materials including pe4booster, PETN, TNT, C4 and B explosives. The results indicate that with the increase of density, detonation velocity, and detonation pressure, the velocity and the length diameter ratio of the front EFP and rear EFP increase with different laws. With the increase of explosive material density, the velocity and the length diameter ratio of EFPs increase gradually, but the increasing rate decreases gradually. As the detonation velocity increases, the velocity of EFPs increase gradually, but the increasing rate decreases gradually. The length diameter ratio of EFPs decreases first and then increases gradually, showing an "s"-shaped change law. With the increase of explosive detonation pressure, the velocity of EFPs increase gradually, but the increasing rate decrease gradually. The length diameter ratio of the front EFP shows a parabolic growth law with the increase of detonation pressure, and the length diameter ratio of the rear EFP shows an "s"-shaped change law with the detonation pressure
Optimization on the jet characteristics of the main nozzle of hot-blowing snow removal device
Get PDFThe exhaust devices used by snow removal vehicles are mainly based on hot-blowing snow removal. Due to the inherent characteristics of the turbojet engine such as low flow rate and high exhaust temperature, the modified hot-blowing snow removal device has problems of low snow removal efficiency and the possibility of ablation and damage to the road surface. In order to solve the problem, transforming the turbofan engine with a high flow rate and a low exhaust temperature into a hot-blowing snow removal device is an important improvement to achieve efficient and safe snow removal operations. In order to convert a medium bypass ratio turbofan engine into a hot-blowing snow removal device, the computational fluid dynamics (CFD) software CFX was used to analyze the internal and external flow field characteristics of the main nozzle of an exhaust device under the 60 % rated condition of the engine. The effective area sizes of the jet velocity and temperature predicted by the external flow field were used to optimize the layout of the main nozzle
Application of A* algorithm in intelligent vehicle path planning
Get PDFPath planning is one of the important directions in the field of intelligent vehicles research. Traditional path planning algorithms generally use Dijkstra algorithm, Breadth-First-Search (BFS) algorithm and A* algorithm. Dijkstra algorithm is a search-based algorithm, which can search to an optimal path, but the disadvantage is too many expansion nodes, which leads to insufficient search efficiency. BFS algorithm is a heuristic search algorithm, which reduces the disadvantage of too many expansion nodes and improves the search efficiency by heuristic function. A* algorithm is a heuristic search algorithm that combines Dijkstra’s algorithm and BFS algorithm, which has higher search efficiency and can search to an optimal path at the same time, but it is still lacking in the search mode and smoothness of the planned route. This paper first introduces the general path planning algorithm, then introduces and analyzes the A* algorithm, and proposes improvement measures for its shortcomings; finally, the executability and effectiveness of the improved algorithm are tested using simulation, and compared with the traditional A* algorithm, and the results show that the improved A* algorithm has good effect on path planning of intelligent vehicles